feat(auth): add configurable email verification enforcement

Auth:RequireEmailVerification (default off) gates whether local
register requires confirming email before login. OAuth new-user paths
are untouched -- Google/Microsoft already assert a verified email.
Adds verify-email and resend-verification-email endpoints, mirroring
the existing reset-password enumeration-avoidance and rate-limiting
patterns, plus a login-embedded resend affordance and a verify-email
landing page on the frontend.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

JobTrackerApi/Controllers/AuthController.cs

@@ -46,6 +46,7 @@ public sealed class AuthController : ControllerBase
         var googleEnabled = !string.IsNullOrWhiteSpace((_cfg["Auth:GoogleClientId"] ?? string.Empty).Trim());
         var microsoftEnabled = !string.IsNullOrWhiteSpace((_cfg["Auth:MicrosoftClientId"] ?? string.Empty).Trim());
         var allowRegistration = _cfg.GetValue("Auth:AllowRegistration", false);
+        var requireEmailVerification = _cfg.GetValue("Auth:RequireEmailVerification", false);
 
         return Ok(new
         {
@@ -54,6 +55,7 @@ public sealed class AuthController : ControllerBase
             microsoftEnabled,
             localEnabled = true,
             allowRegistration,
+            requireEmailVerification,
         });
     }
 
@@ -113,6 +115,14 @@ public sealed class AuthController : ControllerBase
 
         await _users.ResetAccessFailedCountAsync(user);
 
+        // Same enumeration-avoidance discipline as the password-check branch above: this only
+        // runs once the password is already confirmed correct, so it can never be used to probe
+        // whether an email is registered.
+        if (_cfg.GetValue("Auth:RequireEmailVerification", false) && !user.EmailConfirmed)
+        {
+            return StatusCode(StatusCodes.Status403Forbidden, new { error = "email_not_verified" });
+        }
+
         return await CompleteSignInAsync(user, request.RememberMe, "local", cancellationToken);
     }
 
@@ -133,13 +143,28 @@ public sealed class AuthController : ControllerBase
         var existing = await _users.FindByEmailAsync(email);
         if (existing is not null) return BadRequest("User already exists.");
 
-        var user = new ApplicationUser { UserName = email, Email = email, EmailConfirmed = true };
+        var requireEmailVerification = _cfg.GetValue("Auth:RequireEmailVerification", false);
+        var user = new ApplicationUser { UserName = email, Email = email, EmailConfirmed = !requireEmailVerification };
         var res = await _users.CreateAsync(user, password);
         if (!res.Succeeded)
         {
             return BadRequest(string.Join("; ", res.Errors.Select(e => e.Description)));
         }
 
+        if (requireEmailVerification)
+        {
+            try
+            {
+                await SendVerificationEmailAsync(user, cancellationToken);
+            }
+            catch (Exception ex)
+            {
+                // ponytail: don't fail registration over a flaky email send -- the account is
+                // created either way, the user can request a fresh link via resend-verification-email.
+                _logger.LogError(ex, "Failed to send verification email to {Email}", user.Email);
+            }
+        }
+
         return await CompleteSignInAsync(user, request.RememberMe, "local", cancellationToken);
     }
 
@@ -662,6 +687,82 @@ public sealed class AuthController : ControllerBase
         return NoContent();
     }
 
+    public sealed record VerifyEmailRequest(string UserId, string Token);
+
+    [HttpPost("verify-email")]
+    [AllowAnonymous]
+    [EnableRateLimiting("auth-email")]
+    public async Task<IActionResult> VerifyEmail([FromBody] VerifyEmailRequest request)
+    {
+        var userId = (request.UserId ?? string.Empty).Trim();
+        var token = request.Token ?? string.Empty;
+
+        if (userId.Length == 0) return BadRequest("UserId is required.");
+        if (token.Length == 0) return BadRequest("Token is required.");
+
+        var user = await _users.FindByIdAsync(userId);
+        if (user is null) return BadRequest("Invalid or expired link.");
+
+        var res = await _users.ConfirmEmailAsync(user, token);
+        if (!res.Succeeded)
+        {
+            return BadRequest("Invalid or expired link.");
+        }
+
+        return NoContent();
+    }
+
+    public sealed record ResendVerificationEmailRequest(string Email);
+
+    [HttpPost("resend-verification-email")]
+    [AllowAnonymous]
+    [EnableRateLimiting("auth-email")]
+    public async Task<IActionResult> ResendVerificationEmail([FromBody] ResendVerificationEmailRequest request, CancellationToken cancellationToken)
+    {
+        var email = (request.Email ?? string.Empty).Trim();
+        if (email.Length == 0) return NoContent();
+
+        // Mirrors request-password-reset's enumeration-avoidance: always NoContent, only actually
+        // send when there's a matching local account that still needs verifying.
+        var user = await _users.FindByEmailAsync(email);
+        if (user is null || user.EmailConfirmed || string.IsNullOrWhiteSpace(user.Email) || !await _users.HasPasswordAsync(user))
+        {
+            return NoContent();
+        }
+
+        try
+        {
+            await SendVerificationEmailAsync(user, cancellationToken);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send verification email to {Email}", user.Email);
+            return EmailDeliveryUnavailable("Verification email could not be sent right now. Please try again later.");
+        }
+
+        return NoContent();
+    }
+
+    private async Task SendVerificationEmailAsync(ApplicationUser user, CancellationToken cancellationToken)
+    {
+        var token = await _users.GenerateEmailConfirmationTokenAsync(user);
+
+        var baseUrl = (_cfg["App:PublicBaseUrl"] ?? string.Empty).Trim().TrimEnd('/');
+        if (string.IsNullOrWhiteSpace(baseUrl))
+        {
+            baseUrl = $"{Request.Scheme}://{Request.Host}";
+        }
+
+        var link = $"{baseUrl}/verify-email?userId={Uri.EscapeDataString(user.Id)}&token={Uri.EscapeDataString(token)}";
+
+        await _email.SendAsync(
+            user.Email!,
+            "Verify your email",
+            $"Welcome to Jobbjakt! Please verify your email address to finish setting up your account.\n\nVerification link:\n{link}\n\nIf you did not create this account, you can ignore this email.",
+            cancellationToken
+        );
+    }
+
     private IActionResult EmailDeliveryUnavailable(string detail)
     {
         return Problem(statusCode: StatusCodes.Status503ServiceUnavailable, title: "Email delivery unavailable", detail: detail);